Guitar, and method of manufacturing the same



Feb. 7,1967. C, LA FENDER 3,302,507

GUITAR, AND METHOD OF MANUFACTURING THE SAME Filed June 7, 1963 4 Sheets-Sheet 1 c. l.. FENDER 3,302,507

GUITAR, AND METHOD OF MANUFACTURING THE SAME 4 Sheets-Sheet 2 Feb. 7, 1967 Filed June v, 1965 Feb. 7, 1967 C. L. FENDER 3,302,507

GUITAR, AND METHOD OF MANUFACTURING THE SAME Filed June '7, 196s 4 sheets-sheet s ,arrow/Erf Feb 7, 1967 c. n.. FENDER i GUITAR, AND METHOD oF MANUFACTURING 'rms sum Filed June v. 196s nited States atent 3,302,507 GUITAR, AND METHOD F MANUFACTURING THE SAME Clarence L. Fender, Fullerton, Calif., assigner, by mesne assignments, to Columbia Broadcasting System, Inc.,

New York, N.Y., a corporation of New York Filed June 7, 1963, Ser. No. 286,216 24 Claims. (Cl. 84-267) This invention relates to a guitar or like stringed instrument, and to a method of manufacturing and adjusting the same. More specifically, the invention relates to what is commonly termed an acoustic guitar since it has a hollow body and is not normally provided with electrical pickup means.

It has previously been proposed to provide brace means in the hollow body of an acoustic guitar. However, such brace means were not so constructed that the sound generated by the instrument was substantially improved, in comparison to guitars in which no brace means are employed. Furthermore, and very importantly, the brace means of prior-art acoustic guitars were not adapted to be periodically adjusted, and at any desired time throughout the life of the instrument, in such manner as to achieve desirable results including generation of a superior sound.

In view of the above and other factors relative to conventional guitars (and similar instruments) of the acoustic type, it is an object of the present invention to provide an acoustic guitar which is so adjusted both during and subsequent to manufacture that the musical qualities of the generated sound are greatly enhanced.

Another object of the invention is to'provide an acoustic guitar incorporating means to eifect periodic adjustment of the internal truss or brace for the hollow body, so that the, face of the body may be maintained substantially free of strain and distortion.

Another object is to provide an acoustic guitar incorporating combination neck-truss and body-truss means which so interact with each other that the diaphragm portions of the body are preevnted from being distorted substantially, and which are independently adjustable at any time during the life of the instrument.

Another object is to provide a method of manufacturing and adjusting an acoustic guitar, of the internallybraced type, in such manner that the sounds generated thereby are greatly superior to the sounds produced by prior-art guitars.

Another object is to provide an acoustic guitar incorporating shim means to adjust the inclination of the neck relative to the body, thereby permitting achievement of desired spacing between the strings and the forward frets, and without distorting the body of the guitar.

Another object is to provide an acoustic guitar incorporating novel stop means associated with the neck and the neck block, such means being adapted to protect the top sound board from stress or distortion.

Another object is to provide an acoustic guitar the neck of which may be completely manufactured as a separate subassembly and then readily connected to the body by means of a plurality of screw fasteners, in combination with stop means to prevent the neck from eifecting distortion of the diaphragm portions (sound boards) of the body.

Another object is to provide an improved body brace or truss for an acoustic guitar, such truss being adjustable at various times during the life of the instrument in order to counteract the effects of string tension.

Another object is to provide an acoustic guitar incorporating body-truss means which may be readily adjusted from the exterior of the body.

These and other objects will become apparent from the following detailed description taken in connection with the accompanying drawings in which:

FIGURE l is a plan view illustrating an acoustic guitar constructed in accordance with the present invention;

FIGURE 2 is an enlarged horizontal central sectional view, looking in a downward direction, illustrating the guitar body and the adjustable body-truss means incorporated therein;

FIGURE 3 is a fragmentary longitudinal vertical sectional view taken on line 3 3 of FIGURE l and showing the truss means in the neck, and the manner of association thereof with the truss means in the body;

FIGURE 4 is an enlarged transverse sectional view taken on line 4--4 of FIGURE 3;

FIGURE 5 is an enlarged fragmentary vertical sectional view on line 5-5 of FIGURE 2, showing a means for varying the compressive forces in the body truss;

FIGURE 5a is a sectional view corresponding generally to FIGURE 5 but illustrating a modification wherein the truss-adjustment means for the body is readily operable from a point outside the guitar;

FIGURES 6 and 7 are fragmentary vertical views, primarily in section, illustrating the shim means adapted to adjust the angular position of the neck relative to the body; i

FIGURE 8 is a horizontal sectional view corresponding generally to FIGURE 2, but looking in au upward direction;

FIGURE 9 is a schematic longitudinal sectional view showing the types of forces present in various portions of the instrument; and

FIGURE 10 is a composite view illustrating the crosssectional shapes of various brace members shown in FIG- URES 2 and 8.

The acoustic guitar of the present invention is illustrated to comprise a hollow body 10 and a neck 11 which are formed independently of each other, as complete subassemblies, and then adjustably connected by means 12 (FIGURE 3) to be described hereinafter. Neck-truss means 13 (FIGURE 3) are provided to adjust the curvature of the neck 11, and body-truss means 14 (FIGURE 2) are provided to prevent the body from being distorted substantially, and to improve greatly the sound produced by the instrument. Such neck-truss 13 and body-truss means 14 cooperate with each other and with the connector means 12, as will be indicated subsequently.

Proceeding rst to a description of the body 10, this comprises a wooden rim 16 which may be formed in traditional shape, comprising a substantially completely closed curve. Wooden lining strips 17 and 18 are laminated to the interior surface of rim 16, at the upper and lower edges thereof. A large, strong neck block 19 is rigidly secured to the interior surface of rim 16, for example .by gluing, being located at the central portion of the neck end of the rim. The illustrated neck block 19 is formed of three sections 20-22 which are laminated together and are generally trapezoidal in shape. The outer sections 20 and 22 are formed of hardwood, whereas the inner section 21 may be a relatively soft wood in order to decrease the weight of the instrument. A tail block 23 is adhesively secured t0 rim 16 diametrically opposite from the neck block, along the axis of the guitar body. The tail block has a central opening or passage 24 (FIG- URE 5) therethrough, such passage being adapted to receive a portion of the body-truss means 14 as will be described subsequently.

Upper and lower thin wooden diaphragms or sound boards 26 and 27 are glued to the edges of rim 16, and to the neck and tail blocks. Such sound boards, comprising the face and back of the body, are substantially parallel to each other. 'Ille sound boards are so oriented that the grain of the wood is parallel to body-truss 14.

The lower diaphragm (back) of the instrument covers the entire opening defined by rim 16. The upper diaphragm (face) of the body does not cover the entir opening, being instead formed with a central sound hole or opening 28 `and with a gap 29 (FIGURE 4) which extends from the sound hole 28 to the head end of the face, parallel to the axis of the body. Such gap 29 registers with a channel 31 (FIGURE 4) which is formed in the upper portion f neck block 19 for reception of the base of neck 11. The channel 31 forms part of the connector means 12 which associates the neck with the body.

The face and back 26 and 27 of body 10 are internally provided with wooden braces 32 which are adhesively secured thereto. Those bracesv on the back are shown in FIGURE 2, whereas those on the face are shown in FIGURE 8. The braces are shown in crosssection in FIGURE 10, each different type of brace being given a different letter. Thus, braces 32b shown in FIGURE 2 are indicated in section at 32b in FIGURE 10. The ends of the various cross-braces are beveled or tapered as indicated at 32x.

Proceeding next to a description of the neck 11, which is formed as a completely separate sub-assembly independent of body 10, this comprises an elongated wooden base portion 33 having a rectangular inner end which is dimensioned to seat in the above-indicated channel 31 in neck block 19, as shown in FIGURES 3-4. Except for the rectangularly-sectioned portion which seats in channel 31, the neck base 33 has a rounded lower surface 34 indicated in FIGURES 6 and 7.

The upper surface 36 (FIGURE 4) of the neck base 33 is porvided with a groove 37 along the great majority of the length of the neck, and in the center portion thereof. More specifically, groove 37 extends between points A and B indicated in FIGURE 3, being relatively shallow adjacent points A and B and relatively deep at point C midway therebetween. The bottom wall 38 of the groove lies along a continuous curve, for example comprising an arc of a large-diameter imaginary circle having an axis disposed perpendicular to a plane which contains the axis of neck 11 and is perpendicular to surface 36. The sidewalls of groove 37 are generally perpendicular to the surface 36, whereas the bottom wall of the groove may be made concave to receive a truss rod 39 as will be indicated subsequently relative to the description of neck-truss means 13.

The neck further comprises a wooden inlay member 41 which is disposed in groove 37 above the truss rod 39. The lower surface of inlay member 41 is arcuate and generally parallel (FIGURE 3) to the bottom wall of groove 37. The upper surface of the inlay member is su'bstantially flush with surface 36. Inlay 41 is coated with a suitable glue or adhesive before insertion into groove 37, so that it will be rigidly retained therein.

The neck further comprises a wooden fret board 42 shaped correspondingly to the upper surface 36 of neck base 33, being mounted thereover by a suitable glue or adhesive. Such fret board, whichcontains the usual longitudinally-spaced frets 43 (FIGURE 1), conceals the inlay member 41 and associated components.

Formed integrally with the outer end of neck base 33 is a conventional head 44 -containing tuning screws 46 to which the guitar strings are connected, under tension, as shown in FIGURE 1. Such strings are indicated collectively by the reference numeral 47, and extend generally in a plane parallel to that of the fret board to a 'bridge 48 which is mounted on a central part of face 26. The strings are disposed in spaced and generally parallel relationship relative to each other, and pass over the sound hole 28 in conventional manner.

Proceeding next to a description of the connector means 12 for removably securing the neck sub-assembly 11 to the bodyI sub-assembly 10, this comprises a plurality of elongatedslcfrcefvvs 50, a stop or key member 51, and shims 52 (FIGURES 6 and 7). The screws 50 extend upwardly, best shown in FIGURES 3 and 4, through the bottom sound board 27 and the neck block 19 into the rectangularly-sectioned portion of the neck base 33. Four such screws 50 are illustrated, two extending upwardly through bores in neck-block portion 20 and the remaining two through bores in neck-block portion 22. Each set of two screws 50 is Vdisposed in one of two planes which are perpendicular to the axis of body 10. The screws are also perpendicular to the plane of the strings, and to face and back 26 and 27. The upper threaded ends of the screws straddle truss rod 39 as shown in FIGURE 4.

The stop or key 51 is illustrated to comprise a metal cylinder or dowel which is disposed in corresponding registered recesses or bores in the central component Z1 of the neck block and in the base 33 of the neck. The upper end of stop 51 is disposed a short distance below the adjacent portion of truss rod 39.

From the above it will be understood that the screws 50 maintain the forward end of the neck firmly in neckblock channel 31, whereas the stop or key 51 absorbs the thrust which is created between the neck and body dueto the tensioned condition of strings 47. The neck extends inwardly the full distance to sound hole 28, being entirely unconnected to the face or upper sound board 26 except through the neck block 19 and associated components. Thus, because of the action of the screws 50 and stop 51, there is no strain created in the face 26 due to direct action of the neck and the associated strings. Furthermore, as will be described below, there is no substantial strain or distortion set up in the face 26 for any reason, such strain being prevented by the body-truss means 14. Y

The four screws 50 may extend upwardly through a metal plate 53 which serves as a washer as Well las a decorative element.

The described manner of connecting the neck to the body is to be compared with prior-art systems wherein a neck base is provided externally of the rirn k16.V Such neck base and associated neck components were diicult to mount to the body, could not be completely sub-assembled, and could not be removed from the body. Furthermore, the relationship was such that the tension of the guitar strings operated directly on face 26 to distort the same.

A further defect of many prior-art acoustic guitars is that the fret-board or fingerboard portion of the neck extends over and adjacent the face (upper sound board) of the body. Accordingly, upward tilting or racking of the outer neck portion causes the inner fretboard portion to press down on, and distort, the face or upper sound board. Such distortion adversely affects the sound generated by the instrument. v

Another and basic disadvantage of prior-art systems for connecting the neck to the body relates to the difliculty or complexity of adjusting the angular position of the neck relative to the plane of the face. Such adjustment in angular position is readily effected, in the present guitar, by merely inserting one or more shims 52 between the upper surface of neck block 19 and the lower surface of neck base 33, as shown in FIGURES 6 and 7. In FIGURE 6, a shim 52 is shown as being disposed relatively adjacent sound hole 28, so that the neck 11 is caused to be inclined downwardly a slight distance relative to the plane of face 26. In FIGURE 7, a shim is shown as located relatively adjacent thehead, the head then being elevated;

The described adjustment in the angular orientation of the neck relative to the body is important in determining the spacing between the strings 47 and those frets 43 (FIGURE 1) which are relatively adjacent body 10 (the forward frets). Such adjustment in angular position cooperates with the adjustment of the shape of neck 11, caused by the neck-truss means 13 next to bedescribed,

to permit the guitarist to 'achieve a very precise spacing Proceeding to a further description of the neck-truss means 13, this comprises the previously-indicated truss rod 39 which has integrally formed at the outer end thereof a square portion S5, the latter being seated in a corresponding square recess in neck base 33 beneath fret board 42. Thus, the truss rod 39 may not rotate in its groove 37. The inner or forward end of the truss rod is threaded to receive an elongated cylindrical nut 56, such nut being seated rotatably in a counterbore in the inner end of neck base 33. The slotted inner end of the nut is disposed immediately adjacent the sound hole 28, so that the nut may be turned (after removal or loosening of the strings 47) to adjust the degree of tensioning of the truss rod 39. Such rod is coated with wax, as indicated generally in FIGURE 4, to permit a certain degree of movement thereof in groove 37.

With the described construction of the neck-truss means 13, it is a simple matter for the guitarist to adjust precisely the curvature of neck 11. When the nut 56 is turned in a direction effecting drawing of the threaded end of truss rod 39 into the nut, the tension of the truss rod is increased substantially and causes the rod to tend to become straight. This has the effect of elevating the central portions of the truss rod, thereby elevating the central portions of the entire neck relative to the ends thereof. Turning of the nut in the opposite direction relaxes somewhat the tension in the truss rod, thereby lowering the central regions of the neck relative to the end regions. It follows that the spacing between the various frets 43 and the strings 47 may be regulated, such regulation being accomplished in combination with the use of the shims 52 as stated above. It is to be understood that the tensioned strings te-nd to cause the neck to bow downwardly in its central portions.

The body-truss means 14 comprises, as best shown in FIGURES 2, 3, 5 and 8, a tubular metal rod 57 the neck end of which is fitted tightly (preferably a press t) into a cylindrical opening or recess 58 at the center of neckblock 19. The rod extends at least a major portion of the distance through the neck block. The tail end of the tube 57 receives a metal plug 59 (FIGURE 5) having a shoulder 60, such plug being integral with a bolt or threaded shaft 61 which projects into the previously-described opening 24 in tail block 23. A nut 63 is mounted on bolt 61, and serves to press a washer 64 against the inner surface of the tail block. Thus, turning of nut 63 tends to shift the shoulder 60 more tightly against the end of truss rod 57, compressing the same to achieve various advantages as will be stated hereinafter.

The portion of bolt 61 which is disposed in opening 24 is bored and tapped to receive a cap screw 65. Such screw serves to mount to the tail portion of body a button 66 to which one end of the guitar strap 67 (FIGURE 1) is removably secured. The other end of strap 67 is secured to neck block 19 by means of the cap screw 68 and associated button 69 shown in FIGURE 3. It follows that the strap 67 may be employed to support the guitar without creating any stress in neck 11.

Referring next to FIGURE 5a, a modified construction is illustrated wherein the tail end of truss rod 57a is internally threaded to receive an elongated bolt 71 having a slotted screwhead 72 which is inserted into the opening 24. Welded on or formed integrally with the bolt 71 is a nut or shoulder 73 which bears against a washer 74. With the described construction,` a screwdriver inserted into opening 24 from the exterior of the guitar body may be employed to rotate the bolt 71 and thus move it into or out of the threaded portion of truss rod 57a. The nut (which forms a shoulder means) then bears against the washer 74 and thus against tail block 23, again creating a compressive force in truss rod 57a as indicated above.

Description of the method of manufacture and adjustment v Proceeding next to a description of the method of manufacturing and adjusting the guitar, lim 16, neck block 19, tail block 23 and body-truss me-ans 14 are first disposed in a suitable collar or jig. Nut 63 (FIGURE 5) is then turned until the external portion of the rim 16 at the neck and tail portions of the guitar bear against the collar, with reasonable pressure. The adhesive (previously applied) between the neck and tail blocks and rim 16 is then allowed to set. Thereafter, nut 63 is rotated suciently, in its compression-reducing direction, to permit withdrawal of the rim from the collar. After removal of the body from the collar, the sound boards 26 and 27 are glued to the rim, as Well as to the neck and tail blocks.

A special wrench is then inserte-d (after all adhesive is thoroughly dry) through the sound hole 28 and employed to turn nut 63 in such direction as to create a compressive force in truss rod 57. Such compressive force is substantial, being determined as will be stated hereinafter, but iS insucient to destroy or damage the joints between the rim and the sound boards. The embodiment of FIGURE 5a may be employed and the compressive force created without need of a special wrench, there being instead utilized a screwdriver which is inserted into the bore 24.

It is to be understood that the brace elements 32a-32d, and lining 17-18, are adhesively secured to the various body elements at suitable times during construction of the body. The lining 17-18 is pre-formed, which increases the strength of the body.

The complete neck sub-assembly 11, constructed as described in detail above, is readily mounted to the complete body sub-assembly 1t). This is accomplished by merely disposing the end of neck base 33 in channel 31 (FIG- URE 4), after first inserting the stop or key 51. The screws 50 are then screwed into the neck base, and the shims 52 (FIGURE 6 and 7) are employed as previously stated to determine the angle of the neck relative to the body. One advantage of the present construction is that the inner end of the neck may, if desired, be extended inwardly to a central part of sound hole 28.

rThe strings 47 and strap 67 (FIGURE 1) are then mounted on the instrument as indicated above, and it is noted whether or not the distances between the strings and each fret 43 are as desired. If not, the strings are removed or loosened and a screwdriver is employed to turn the element 56 (FIGURE 3) to either tension or relax the truss rod 39 in neck 11, thereby adjusting the curvature of such neck. The truss rod 39 thus cooperates with shims 52 to achieve precise desired spacings between the strings and each fret 43.

There will next be described the extremely important method by which the compression-adjusting nut 63 of the body truss 14 (including the truss rod 57) is adjusted. Particular reference is made to schematic FIGURE 9, in which the types of forces are designated by arrows. Arrows pointing toward each other indicate compression, whereas arrows pointing away from each other indicate tension.

In FIGURE 9, the portion of the guitar face (or upper diaphragm) 26 which is between bridge 48 and tail block 23 is designated 26a, whereas the portion of the face between the bridge and the neck lblock 19 is designated 26h. It is to be remembered that the wood forming the face 26a-26b and the 'back 27 is so oriented that the grain is parallel to body truss rod 57.

Stated briefly, the nut `63 is turned to such position that portion 26h of the guitar face is not under substantial tension or substantial compression, but instead is in a neutral or floating reltaionship. Thus, sucient tension must be developed in the face portion 26a to counteract the very considerable (over one hundred pounds) tension in the strings 47.

Upon reference to the arrows indicated in FIGURE 9, it will be understood that the tension present in strings 47 and in face portion 26a is counteracted by the cornpression present in neck 11 and in body truss 57. The back 27 of the body is also under tension, it being pointed out that the region where the washer 64 (FIGURE 5) engages tail block 23 operates as a fulcrum permitting pivotal movement of the tail block to create the indicated tensioned relationship in both the back 27 and the face portion 26a.

The described relationship by which the portion 26h of the face is not substantially stressed in either tension or compression, and by which the portion 26a of the face andy the back 27 are each uniformly tensioned, substantially improves the sound generated by the instrument. It will be understood that surfaces which are under uniform tension will vibrate in a much more regular and desirable manner than will surfaces which are subjected to numerous random stresses and are considerably warped. The face portion 26h, which is not stressed substantially, is free to vibrate in a manner which is completely unimpeded, so that the maximum possible musical eifect is generated. It is pointed out that the wood in the tensioned regions 26a and 27 does not stretch excessively, due to the orientation of the grain longitudinally of truss rod 57.

From the above, it will be understood that there is no substantial compression in any portion of the face or back of the body. Consequently, there is no dishing, warping, racking, etc., which is characteristic of priorart instruments. Because of the absence of compression, the braces 32a-32a. (FIGURE 10) may be substantially smaller than in prior-art instruments, yet neither the face nor back of the instrument will become dished or otherwise out of parallel. In addition, the wood forming the face or 'back may be relatively thin. Because of the fact that the wood may be thin, and the braces may Ibe small in section, the sound generated by the instrument is stronger than in the case of prior-art instruments.

It is emphasized that the guitar may, at any time, be returned to the factory so that the truss-rod nut 63 may be adjusted to compensate for the effects of aging of the instrument. 'Such nut 63 is then adjusted, as stated above, until there is substantially no tension or compression in the portion 2611 (FIGURE 9) of the guitar face.

The presence or absence of stress in the guitar face portion 26h (FIGURE 9) may be determined by various conventional means, including strain gauges of an electrical or mechanical nature. Such presence or absence of stress should be determined when the guitar is in its normal playing condition. However, -as previously indicated, the nut 63 should be tightened to approximately the desired degree (empirically determined) before the strings are mounted. Minor adjustments may then be made in the setting of nut 63 (-or 73) after the strings are mounted.

It is emphasized that the neck-truss means 13 and the body-truss means 14 cooperate with each other, through the novel connection means 12 at neck block 19, to absorb ythe entire tension of the guitar strings 47 in a manner which does not stress the guitar face and back 26, 27. Furthermore, as described in detail heretofore, the connection between the neck 11 (including necktruss means 13) `and body 10 (including body-truss means 14) is such that any desired spacings may be achieved between the frets 43 and strings 47.

All of the described beneficial results are achieved in an instrument which may be manufactured in a relatively economical manner, particularly since both the neck and body may be completely sub-assembled independently of each other.

The foregoing detailed description is to be clearly understood as given by way of illustration and example only, the spirit and scope of this invention being limited solely by the appended claims.

I claim:

1. An acoustic guitar, which comprises a hollow wooden .body having top and bottom sound boards generally parallel to each other,

a neck,

means to connect said neck to said body,

neck-truss means mounted longitudinally is said neck, said neck-truss means being adjustable to vary the curvature of said neck,

body-truss means mounted in said body in general alignment with said neck-truss means,

said body-truss means being adjustable independently of said neck-truss means to vary the forces in said top sound board,

means vto operably associate with each other the adjacent end portions of said neck-truss means and body-truss means, and

a plurality of guitar strings mounted in tensioned relationship over said neck and over said top sound bo'ard and connected thereto.

2. A guitar, which comprises a hollow body formed as a first separate subassembly,

said `body having a neck-receiving channel therein, an elongated neck formed as a second separate subassembly and having 'an inner end portion seated in said channel,

means to removably secure said end portion of said neck Vto said body whereby to retain said end portion in said channel,

a stop element operably associated with said end portion and with said body at said channel and serving to absorb the thrust present in the strings of the instrument without straining the top sound board of said body, and

a plurality of strings mounted over said body and over said neck in tensioned relationship,

said strings being connected to said top sound board and to 'a portion of said neck remote from said body.

3. The invention as claimed in claim 2, in which truss means are mounted in said hollow body longitudinally of said neck,

said truss means being connected to the tail portion of said body and to the portion of said body which is associated with said neck.

4. The invention 'as claimed in claim 2, in which truss means are provided longitudinally in said neck.

5. The invention as claimed in claim 2, in which neck-truss means are provided in said neck longitudinally thereof, in which body-truss means are provided in said body longitudinally thereof, and in which means are provided to connect said neck-truss means and body-truss means to each other independently of said top sound board,

said last-named means including said stop element.

6. A guitar, which comprises 'a body having parallel top and bottom sound boards connected by a rim,

said top sound board having a sound hole therein, a neck block disposed entirely within said body and secured to said rim,

said neck block extending the entire distance between said top and bottom sound boards and terminating adjacent said sound hole, said neck block having a channel therein which extends between said rim and said sound hole,

a neck having a portion seated in said channel a'nd extending to said sound hole,

means to connect said neck portion to said neck block and to absorb the thrust exerted between said neck and body by the strings of the guitar,

truss means mounted in said neck,

said truss means comprising .an elongated truss rod disposed longitudinally in said neck and a threaded element mounted rotatably in said neck, and

a plurality of strings mounted over said body and neck in tensioned relationship.

7. The invention as claimed in claim 6, in which body- 9 ti'iiss means are niunte'd in said body between said neck block and a tail block which is provided in said body remote from said neck block and diametrically opposite thereto.

8. An acoustic guitar, which comprises a hollow body having generally parallel face and back portions connected by a rim,

a neck connected to one edge of said body and extending outwardly therefrom,

a bridge mounted on said face portion in spaced relationship from said neck and also from the tail region of said body diametrically opposite said neck,

a plurality of guitar strings connected in tensioned condition between said bridge and the end of said neck remote from said body, and

a truss element mounted within said body generally parallel to said strings,

said truss element extending between opposite edge portions of said body, said truss element incorporating 'adjustable means to create varying degrees of compression there- 1n,

said adjustable means being so set that said back portion and the region of said face portion between said bridge and said tail region are under tension, 'and the region of said face portion between said bridge and said neck is under neither substantial compression nor substantial tension.

9. The invention as claimed in claim 8, in which said face portion and back portion are formed of thin sheets of wood having the grain thereof substantially parallel to said strings.

10. The invention as claimed in claim 9, in which wooden brace means are secured to the interior surfaces of said sheets of wood.

11. In a method of manufacturing and adjusting an acoustic guitar having a hollow body with generally parallel face and back portions,

a neck extending outwardly from said body, and tensioned strings extending between the distal end of said neck and a bridge located in a central region of said face portion, the steps of:

providing interiorly of said body and longitudinally of said strings a body truss which is adjustable to vary the forces present in said face and back portions of said body, and

adjusting said body truss until said back portion and the region of said face portion on the opposite side of said bridge from said neck are under tension, and the region of said face portion between said bridge and said neck is under neither substantial tension nor substantial compression.

12. The invention as claimed in claim 11, in which said adjustment step includes lengthening said truss to place the same under substantial compression between diametrically-opposite rim portions of said body.

f 13. The invention as claimed in claim 2, in which said stop element comprises a dowel having portions inserted into cooperating recesses formed in said end portion and in said body at said channel.

14. The invention as claimed in claim 13, in which said dowel is a large diameter metal cylinder, and in which said cooperating recesses are cylindrical and have diameters corresponding generally to those of the dowel portions inserted therein.

15. A guitar, which comprises:

a neck and a body having a plurality of guitar strings mounted thereover and connected thereto in tensioned relationship,

said body comprising a rim and further comprising upper and lower sound boards secured to said rim whereby to detine a chamber between said sound boards and within said rim,

a neck block mounted in said chamber at the neck end of said body,

a plurality of screws extending through said neck block into said neck,

said screws being generally perpendicular to said sound boards, and

a stop or key element adapted to absorb the thrust exerted by said strings.

16. The invention as claimed in claim 15, in which said stop or key element is a relatively large-diameter dowel and is inserted snugly into cooperating recesses formed in said neck block and in said neck.

17. The invention as claimed in claim 15, in which shim means are disposed between said neck and said neck block to adjust the inclination of said neck relative to said body.

1S. The invention as claimed in claim 15, in which said stop or key element is a cylindrical metal dowel extending generally parallel to said screws, the diameter of said dowel being .much larger than the diameter of any of said screws.

19. The invention as claimed in claim 15, in which said upper sound board has a sound hole therein, and in which said neck extends to the vicinity of said sound hole.

20. The invention as claimed in claim 15, in which said neck block has a channel formed therein substantially parallel to said neck, and in which said neck seats in said channel.

21. A guitar, which comprises:

a hollow body having generally parallel top and bottom sound boards connected by a rim,

a neck block disposed within said body and extending between said top and bottom sound boards,

a neck having a portion connected to said neck block,

neck-truss means mounted longitudinally in said neck,

said neck-truss means including an adjustable element adapted to effect variation in the curvature of said neck,

body-truss means mounted in said body longitudinally of said neck and extending between said neck block and the region of said body diametrically opposite said neck block,

said body-truss means including an element adapted to adjust the length of said body-truss means to thereby determine the forces present in said top sound board, and

a plurality of guitar strings mounted over said neck and over said top sound board and connected thereto.

22. The invention as claimed in claim 21, in which said neck portion is seated in a channel formed in said neck block, and in which the means to connect said neck to said neck block at said channel comprises a plurality of elongated screws extending through said neck block and into said neck, said screws extending generally perpendicular to said sounds boards, said connecting means further comprising a dowel element having portions disposed snugly in recesses formed in said neck lblock at said channel and in the adjacent region of said neck portion, said dowel element serving to absorb the thrust exerted by said strings.

23. The invention as claimed in claim 22, in which a shim is mounted in said channel between said neck portion and said neck block and is shaped to determine the inclination of said neck relative to said body.

24. A guitar, which comprises:

a hollow body having generally parallel top and bottom sound boards connected by a rim,

a neck block disposed within said body and extending between said top and bottom sound boards,

a neck having a portion seated in a channel formed in said ne-ck block,

means to connect said neck portion to said neck block at said channel,

said connecting means comprising a plurality of l l elongated screws extending through said neck block and into said neck,

said screws extending generally perpendicular to said sound boards, said connecting means further comprising a dowel element having portions disposed snugly in recesses formed in said neck block at said channel and in the adjacent region of said neck portion, neck-truss means mounted longitudinally in said neck,

said neck-truss means including an adjustable element adapted to eiect Variation in thel curvature of said neck, a shim mounted in said channel between said neck portion and said neck block and shaped to determine the inclination of said neck relative to said 15 body, and a plurality of guitar strings mounted over said neck and over said top sound board and connected thereto.

References Cited by the Examiner UNITED STATES PATENTS 6/1930 Larson 84-291 8/1931 Larson SLP-293 11/1932 Larson 84-291 X 5/ 1933 Turturro 84-293 10/1936 Low 84-293 2/ 1939 Stathopoulo 84-293 12/1953 Prescott 84-291 FOREIGN PATENTS 8/ 1955 Sweden.

RICHARD B. WILKINSON, Primary Examiner.

LEO SMILOW, Examiner.

CHARLES M. OVERBEY, Assistant Examiner. 

1. AN ACOUSTIC GUITAR, WHICH COMPRISES A HOLLOW WOODEN BODY HAVING TOP AND BOTTOM SOUND BOARDS GENERALLY PARALLEL TO EACH OTHER, A NECK, MEANS TO CONNECT SAID NECK TO SAID BODY, NECK-TRUSS MEANS MOUNTED LONGITUDINALLY IS SAID NECK, SAID NECK-TRUSS MEANS BEING ADJUSTABLE TO VARY THE VURVATURE OF SAID NECK, BODY-TRUSS MEANS MOUNTED IN SAID BODY IN GENERAL ALIGNMENT WITH SAID NECK-TRUSS MEANS, SAID BODY-TRUSS MEANS BEING ADJUSTABLE INDEPENDENTLY OF SAID NECK-TRUSS MEANS TO VARY THE FORCES IN SAID TOP SOUND BOARD, MEANS TO OPERABLY ASSOCIATE WITH EACH OTHER THE ADJACENT END PORTIONS OF SAID NECK-TRUSS MEANS AND BODY-TRUSS MEANS, AND A PLURALITY OF GUITAR STRINGS MOUNTED IN TENSIONED RELATIONSHIP OVER SAID NECK AND OVER SAID TOP SOUND BOARD AND CONNECTED THERETO. 